Camera with focal length varying device

ABSTRACT

In a camera which has an automatic focusing device and is arranged to permit a change-over from one focal length of the photo taking optical system thereof to another, the focusing position of the automatic focusing device is arranged to vary in response to the focal length change-over of the photo taking optical system, so that the focusing operation can be always carried out appositely to the selected focal length of the optical system.

This is a continuation of application Ser. No. 561,640 filed Dec. 15,1983.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a camera which permits a change-over of focallength of the photo taking optical system thereof.

2. Description of the Prior Art

During recent years, there have been proposed cameras of the kind havinga focal length varying device which permits photographing at variousfocal lengths such as a normal focal length, a telephoto focal length,etc. In a camera of this kind, however, the F-number of the aperture andthe depth of field of a photo taking optical system will vary as aresult of a focal length change-over. Therefore, the arrangement of theprior art to automatically focus the photo taking optical system bymeans of the automatic focusing device has presented various problems.For example, it has been known, from U.S. Pat. No. 4,183,643, etc., toset a photo taking optical system in a certain predetermined positionwhere the widest in-focus range is obtainable when a distance to anobject to be photographed is undetectable by means of a distancemeasuring circuit in an automatic focusing type camera. Thispredetermined position is generally a hyper-focal point in which theoptical system is focused on a hyper-focal distance with the farthestpoint within the depth of field becoming an infinity distance(hereinafter the predetermined position will be called a fix point).However, the distance from the photo taking optical system to thehyper-focal point is in direct proportion to the square of the focallength of the photo taking optical system and in inverse proportion tothe square of the aperture F-number thereof. In the case of a variablefocal length type camera having a photo taking optical system which isshiftable, for example, for a normal optical system of focal length 40mm (F 2.8) to a telephoto optical system of focal length 70 mm (F 5.6),the hyper-focal point varies to a great extent according to the focallength change-over. Therefore, in case such a variable focal lengthcamera is provided with an automatic focusing device, the probability ofan out-of-focus photographing operation increases under a conditionwhere distance cannot be measured if the above-stated fix point is leftunvarying despite a focal length change-over.

Further, in the case of an automatic focusing type camera provided witha flash device, problems such as under exposure, etc. tend to arise,even when a focusing operation is appositely carried out, because theflash light quantity of the flash device is limited. To be morespecific, between a guide number GN which denotes the flash lightquantity to be emitted from the flash device, an F-number of theaperture of the photo taking optical system and a distance "d" betweenthe flash device and an object to be photographed, there is thefollowing relation: GN=F×d. With the aperture F-number unvarying, alight quantity larger than the guide number of the flash devicetheoretically becomes necessary when the object is located at a longdistance. To solve this problem, there have been proposed, as known fromJapanese Utility Model Application Laid-Open No. Sho 54-18229, etc., anarrangement wherein the shift of a photo taking optical system toward aninfinity position is limited to a distance within a flash photographabledistance range determined jointly by the F-number of the aperture andthe guide number of the flash device (hereinafter this distance will becalled flash device far point) even when the object is located at a longdistance. Thus, the camera is restricted to photographing within a rangewhich can be sufficiently covered with the flash light quantity of theflash device.

However, if a camera of this kind is provided with the focal lengthvarying device mentioned in the foregoing, the above-stated far point ofthe flash device will vary accordingly as the aperture F-number varies,because the F-number varies every time the focal length of the phototaking optical system is shifted. Thus, a camera of this kind alsopresents a problem.

SUMMARY OF THE INVENTION

A first object of the present invention is to provide an automaticfocusing type camera which permits a change-over from one focal lengthof the photo taking optical system thereof to another and in which theautomatic focusing device of the camera is arranged to vary the focusingposition thereof according to the focal length change-over of the phototaking optical system, so that focal point adjustment can be performedappositely to a selected focal length of the photo taking opticalsystem.

A second object of the invention is to provide a camera of theabove-stated kind wherein there are provided a plurality of fix pointsat which the photo taking optical system can be stopped from shiftingwhen an object distance is unmeasurable. The fix points are arranged topermit selection of one of them according to the focal length changeoverof the photo taking optical system, so that focusing accuracy under acondition where distance is not measurable can be increased.

A third object of the invention is to provide a camera of theabove-stated kind wherein, in the event of flash photography, the phototaking optical system is brought to a stop in a position correspondingto the above-stated far point of the flash device for an object locatedat a distance farther than the far point of the flash device in responseto a focal length change-over operation on the photo taking lens so thatthe focusing operation of the automatic focusing device can be carriedout always appositely for flash photography.

These and further objects and features of the invention will becomeapparent from the following detailed description of preferredembodiments thereof taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1(a) and 1(b) are sectional views showing a camera provided with afocal length varying device according to the present invention as firstand second embodiments thereof. FIG. 1(a) is a plan view showing thecamera as in a normal photographing state. FIG. 1(b) is a plan viewshowing the camera in a telephoto state.

FIG. 2 is a schematic plan view partially in section showing a mechanismfor adjusting the shifting extent of a main lens of the firstembodiment.

FIG. 3 is a circuit diagram showing a control circuit included in thefirst embodiment shown in FIG. 2

FIG. 4 is a schematic plan view partially in section showing a mechanismfor adjusting the shifting extent of a main lens of the secondembodiment.

FIG. 5 is a circuit diagram showing a control circuit included in thesecond embodiment shown in FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will be described belowwith reference to the accompanying drawings, in which FIGS. 1a and 1bare sectional views roughly showing the essential parts of a variablefocal length type camera arranged according to the invention as firstand second embodiments thereof. FIG. 1(a) shows the camera in a normalphotographing state and FIG. 1(b) shows it in a telephoto state.Referring to these drawings, a main lens system 2 is carried by a lensbarrel 1. A lens barrel bar 3 is secured to the lens barrel 1 and isarranged in parallel with a photo taking optical axis. The lens barrelbar 3 is fittingly carried by a lens barrel unit 4 at two pointsthereof. Behind the lens barrel 1 is disposed a shutter (not shown)within the lens barrel unit 4. An extender 6 which carries an auxiliarylens system 5 is rotatably disposed on a shaft 7 within a space furtherbehind the lens barrel 1. The shaft 7 is fittingly carried by the lensbarrel unit 4. The extender 6 is urged toward the rear of the camera bya spring (not shown) wound around between the lens barrel unit 4 and theshaft 7. This causes the extender 6 to abut on an adjustment screw (notshown) which is in screwed engagement with the rear face of the lensbarrel unit 4. When the lens barrel unit 4 is drawn out from the stateof FIG. 1(a) to the state of FIG. 1(b), the extender 6 turns on theshaft 7 to bring the auxiliary lens system onto the optical axis of themain lens system 2.

A bellows 10 is disposed between the rear face of the lens barrel unit 4and a light shielding frame plate 9 which forms a dark box part of acamera body 8 with the end faces of the bellows secured to themrespectively.

A support bar 11 is secured to the lens barrel unit 4 and is disposed inparallel with the photo taking optical axis. Meanwhile, a holding plate12 is fittingly engaged with the lens barrel unit 4 and is attached tothe front face of the camera body 8. The support bar 11 is fittinglycarried by the holding plate 12 and is arranged to be slidable at thefront and rear side plate parts of the holding plate 12. The holdingplate 12 also has two ends of a guide bar 13 secured to the front andrear plate parts thereof. The guide bar 13 which is thus arranged inparallel with the photo taking optical axis fittingly engages the otherside of the lens barrel unit 4. The lens barrel unit 4 is thus arrangedto be slidable back and forth relative to the camera body together withthe support bar 11 with the guide bar 13 serving as guide for thesliding movement of the lens barrel unit 4. The camera is provided withan outside casing 14 and a pin 15 for positioning the extender 6.

Next, FIG. 2 shows the shifting extent adjusting mechanism for the lensbarrel 1 of the first embodiment shown in FIG. 1. Referring to FIG. 2, aspring 20 is arranged to urge the lens barrel 1 to move downward asviewed on the drawing. A stop lever 21 is arranged to lock the lensbarrel 1 against the force of the spring 20. The stop lever 21 isprovided with a claw part 21a which is arranged to engage a claw 24 forlocking the lens barrel 1 in its initial position and also to engageratchet teeth 25 for locking the lens barrel 1 in other positionsaccording to information on a distance to an object to be photographed.Further, the stop lever 21 is pivotally carried by a support shaft 22and is urged clockwise by a spring 23. Under a condition aftercompletion of a film winding operation of the camera, the urging forceof the spring 23 causes the claw 21a to engage the claw 24. This bringsthe movement of the lens barrel 1 due to the spring 20 to a stop. Thismovement of the lens barrel 1 is arranged to shift the focal point ofthe main lens system 2 from the nearest distance position to theinfinity distance position thereof. The extent to which the lens barrel1 is shifted is arranged to be detected by a shifting extent detector(not shown).

An armature 26 is secured to the stop lever 21. When power supply iseffected to a coil 27, the armature 26 is attracted by a yoke 28. Withthe armature 26 attracted by the yoke 28, the stop lever 21 is kept inthe position of FIG. 2. A brush 29 for electrical conduction is securedby a pin 30 to the lens barrel 1. The brush 29 is thus arranged to slideover a patterned circuit substrate 31. On the substrate 31 are provideda copper foil piece 31c which is arranged to come into contact with oneof the legs of the brush 29 and copper foil pieces 31a and 31b which arearranged to come into contact with the other leg of the brush 29.

Further, the copper foil piece 31a is arranged to come into contact withthe brush 29 when the lens barrel 1 comes to a position in which theoptical system is focused on a hyper-focal distance in the case ofphotographing with both the main lens system 2 and the auxiliary lenssystem 5 as shown in FIG. 1(b). The copper foil piece 31b is arranged tocome into contact with the brush 29 when the lens barrel 1 comes to aposition in which the optical system is focused on a hyper-focaldistance in carrying out photographing solely with the main lens system2 as shown in FIG. 1(a). Further, the brush 29 is arranged toelectrically connect the copper foil piece 31c to the copper foil pieces31a and 31b.

FIG. 3 shows the control circuit of the first embodiment. Switches 40aand 40b are arranged to turn on and off in response to the focal lengthchange-over of the optical system. The switch 40a turns on when thecamera is set into the telephoto state as shown in FIG. 1(b) while theother switch 40b turns on when the camera is set into the normalphotographing state as shown in FIG. 1(a). One of the terminals of eachof the switches is connected to a constant voltage source Vcc whichbegins to effect power supply in response to the first stroke of adepressing operation on a shutter button (not shown). The other terminalof each of the switches is grounded via a resistor 42 or 43. A switchingtransistor 41 is arranged to be turned on or off by the output of anobject distance detecting circuit 51. The transistor 41 has itscollector connected to the power source Vcc and its emitter grounded viaa resistor 44. Reference numberals 45 and 46 denote two-input AND gates.One of the input terminals of the AND gate 45 is connected to theresistor 42 and the other input terminal thereof to the resistor 44. Oneof the input terminals of the AND gate 46 is connected to the resistor43 and the other thereof to the resistor 44. The output of the AND gate45 is connected to the above-stated copper foil piece 31b while that ofthe AND gate 46 is connected to the copper foil piece 31a. A focusingcircuit 47 is arranged to produce a high level pulse signal when thelens barrel 1 is moved to a position corresponding to the ouput of theobject distance detecting circuit 51. An OR gate 48 is arranged toreceive a signal from the copper foil piece 31c and the pulse signalfrom the focusing circuit 47. The output terminal of the OR gate 48 isconnected to the reset terminal of an RS flip-flop 49 (hereinafter willbe called RS-FF). The RS-FF 49 is arranged to be reset by a pulse signalRS produced by the second stroke of the depressing operation of theshutter button (not shown). The output Q of the RS-FF 49 is arranged toperform on and off control over a switching transistor 50 which isarranged to control power supply to a coil 27. The object distancedetecting circuit 51 is arranged to produce a distance signal to thefocusing circuit 47 when a distance to an object to be photographed isdetected and to produce a high level signal to the base of thetransistor 41 when the object distance is undetectable. This circuitarrangement is well known from the above-cited U.S. Pat. No. 4,183,643,etc. and therefore requires no detailed description.

The following description of the operation of this embodiment which isarranged as described above begins with description of the operationthereof performed when the object distance is detectable by the objectdistance detecting circuit 51.

Under that condition, a distance signal is produced from the objectdistance detecting circuit 51 to the focusing circuit 47. A low levelsignal is supplied from the circuit 51 to the base of the transistor 41.This low level signal turns the transistor 41 off. Accordingly, theinput terminals of the AND gates 45 and 46 connected to the resistor 44are kept at a low level. The AND gates 45 and 46 thus produce low leveloutputs. When the pulse signal RS is produced by the depressingoperation on the shutter button, the RS-FF 49 is set. The level of theoutput Q of the RS-FF 49 becomes high. This turns the transistor 50 onto begin power supply to the coil 27. As a result, the armature 26 isattracted by the yoke 28. The stop lever 21 disengages its claw part 21afrom the claw 24. This allows the lens barrel 1 to be moved by thespring 20 from the nearest distance position to the infinity distanceposition.

In this instance, if the object is located at an infinity distance, thelens barrel 1 causes the brush 29 to electrically connect either thecopper foil piece 31a or 31b to the copper foil piece 31c on its way tothe infinity distance position. However, since both the AND gates 45 and46 are then producing low level outputs, the output of the OR gate 48remains at a low level even when the brush 29 comes into contact withthe copper foil piece 31b or 31a. Therefore, the RS-FF 49 is not reset.The lens barrel 1 is therefore allowed to move on. As a result, the lensbarrel 1 comes to an in-focus position and is stopped there by the stoplever 21 when the power supply to the coil 27 comes to a stop with theRS-FF 49 reset by the output of the focusing circuit 47.

In case that the camera is in the normal photographing state as shown inFIG. 1(a) and that the object distance is undetectable by the objectdistance detecting circuit 51, in that instance the camera operates sothat the switch 40b and the transistor 41 turn on. Therefore, the ANDgate 45 receives two high level inputs and thus produces a high levelsignal. This causes the lens barrel 1 to move. Then, when the brush 29comes into contact with the copper foil pieces 31b and 31c, the outputlevel of the OR gate 48 becomes high to reset the RS-FF 49. The coil 27then ceases to receive power supply. The claw 21a of the stop lever 21comes to engage the ratchet claw 25 to bring the movement of the lensbarrel 1 to a stop.

In this case, therefore, the lens barrel 1 comes to a stop in a positionwhere it is in focus for a hyper-focal distance under the normalphotographing condition.

When the camera is set into the telephoto state of FIG. 1(b), theauxiliary lens 5 enters the photo taking optical system. As a result,the hyper-focal distance of the whole photo taking lens extends towardthe infinity distance. Meanwhile, as mentioned in the foregoing, thecopper foil piece 31a is then located in a position corresponding tothis hyper-focal distance. Since the switch 40 turns on in thisinstance, if the transistor 41 turns on due to the inability of theobject distance detecting circuit 51 to measure the distance, the outputlevel of the AND gate 46 which is connected to the copper foil piece 31abecomes high. Therefore, when the brush 29 electrically connects thecopper foil pieces 31a and 31c, the RS-FF 49 is reset to bring themovement of the lens barrel 1 to a stop. The lens barrel 1 thus comes toa stop at a position where it is in focus for the hyper-focal distanceof the photo taking optical system with the optical system in itstelephoto state.

A second embodiment of the invention is arranged as shown in FIGS. 1, 4and 5. The arrangement as shown in FIG. 1 is identical with the firstembodiment and thus requires no further description thereof. Meanwhile,the arrangement shown in FIGS. 4 and 5 corresponds to the arrangement ofthe first embodiment shown in FIGS. 2 and 3. The parts that are the sameas those shown in FIGS. 2 and 3 are, therefore, indicated by the samereference numerals in FIGS. 4 and 5 and these same parts are omittedfrom the following description.

FIG. 4 shows a mechanism for adjusting the shifting extent of the lensbarrel 1. Referring to FIG. 4, a copper foil piece 31a' is disposed in aposition to come into contact with the brush 29 when the lens barrel 1moves to a position where the optical system is in focus on a flashdevice far-point distance determined by the F-number of the aperture andthe guide number of the flash device which is incorporated in the camera(not shown) in the case of photographing solely with the main lens 2.Another copper foil piece 31b' is disposed in a position to come intocontact with the brush 29 when the lens barrel 1 moves to a positionwhere the optical system is in focus on a flash device far-pointdistance which is determined by the F-number of the aperture and theguide number of the flash device in the case of photographing with boththe main lens 2 and the auxiliary lens 5. Meanwhile, the brush 29 isarranged to electrically connect a copper foil piece 31c' to the copperfoil pieces 31a' and 31b '. The rest of the arrangement is identicalwith the arrangement shown in FIG. 2.

FIG. 5 shows the control circuit arrangement of the second embodiment,which includes switches 40a' and 40b' which are arranged to turn on andoff in response to the focal length change-over of the optical system.The switch 40b' turns on when the camera is set into the telephoto stateas shown in FIG. 1(b), while the other switch 40a' turns on when thecamera is set into the normal photographing state as shown in FIG. 1(a).One of the terminals of each of these switches 40a' and 40b' isconnected to a constant voltage source Vcc which is arranged to beginpower supply in response to the first stroke of a depressing operationon the shutter button (not shown). The other terminal of each of theseswitches is grounded via a resistor 42' or 43'. Another switch 41' isarranged to turn on in response to a charging process initiatingoperation on a flash device (not shown). Alternatively, the switch 41'may be arranged to turn on in response to a pop-up motion of the flashdevice. One of the terminals of the switch 41' is connected to the powersource Vcc while the other terminal of this switch is grounded via aresistor 44'.

Reference numerals 45' and 46' denote two-input AND gates. One of theinput terminals of the AND gate 45' is connected to the resistor 42',while the other is connected to the resistor 44'. The AND gate 46' hasone of its input terminals connected to the resistor 43' and the otherto the resistor 44'. The output terminal of the AND gate 45' isconnected to the copper foil piece 31b', while that of the AND gate 46'is connected to the copper foil piece 31a'. A focusing circuit 47' isarranged to produce a high level pulse signal when the lens barrel 1comes to a position corresponding to the output of a focal pointdetecting circuit (not shown). An OR gate 48' is arranged to receive asignal from the copper foil piece 31c' and the pulse signal producedfrom the focusing circuit 47'. The output terminal of the OR gate 48' isconnected to the reset terminal of an RS flip-flop 49' (hereinaftercalled RS-FF). The RS-FF 49' is arranged to be set by a pulse signal RSproduced in response to he second stroke of the depressing operation onthe shutter button (not shown). The output Q of the RS-FF 49' isarranged to turn on and off a switching transistor 50' which controlspower supply to the coil 27. With the embodiment arranged in thismanner, an ordinary photographing operation without using the flashdevice will first be described. The switch 41' is off in this instance.The input terminals of the AND gates 45' and 46' which are connected tothe resistor 44' are kept at a low level. Accordingly, the output levelsof these AND gates 45' and 46' are low. Under this condition, when thepulse signal RS is produced by the depressing operation on the shutterbutton, the RS-FF 49' is set to make the level of the output Q thereofhigh. The transistor 50' then turns on to allow the power supply to thecoil 27 to begin. As a result, the armature 26 is attracted by the yoke28 to disengage the claw part 21a of the stop lever 21 from the claw 24.The force of the spring 20 the begins to move the lens barrel 1 from thenearest distance position toward the infinity distance position thereof.

If the object to be photographed is located at an infinity distance inthis instance, the lens barrel 1 on its way toward the infinity distanceposition causes the brush 29 to electrically connect the copper foilpiece 31b' or 31a' to the copper foil piece 31c'. Since the outputlevels of both the AND gates 45' and 46' are low at that time, theoutput level of the OR gate 48' never becomes high when the brush 29comes into contact with the copper foil piece 31b' or 31a' and thus doesnot reset the RS-FF 49'. This permits the lens barrel 1 to move onfarther until it is brought to a stop by the stop lever 21 when thepower supply to the coil 27 is cut off with the RS-FF 49' reset.

In case that flash photography is to be carried out with the camera setin the normal photographing state as shown in FIG. 1(a), in theoperation of the embodiment the switches 40a' and 41' turn on in thiscase. Therefore, the levels of both the inputs of the AND gate 46'become high. This causes the AND gate 46' to produce a high levelsignal. Therefore, the lens barrel 1 moves to bring the brush 29 intocontact with the copper foil pieces 31a' and 31c'. Then, the outputlevel of the OR gate 48' becomes high to reset the RS-FF 49'. The powersupply to the coil 27 comes to a stop. The claw 21a of the stop lever 21comes to engage the ratchet claw 25 to bring the movement of the lensbarrel 1 to a stop. In this instance, therefore, the movement of thelens barrel 1 comes to a stop at a position where the optical system isjustly focused on the far point of the flash device for normalphotographing even when the object to be photographed is located at afar distance. Further, in the event that the object is located at a neardistance and the output level of the focusing circuit 47' becomes highbefore the copper foil pieces 31a' and 31c' are electrically connectedto each other, the high level signal thus produced from the circuit 47'resets the RS-FF 49'. The lens barrel 1, therefore, then comes to stopshifting of the optical system at a position where it is accuratelyfocused on the object.

When the camera is set into the telephoto state as shown in FIG. 1(b),the position of the auxiliary lens 5 is shifted to the inside of theoptical system. As a result of that, the aperture F-number of theoptical system becomes larger. This causes the far point of the flashdevice to shift toward the nearest distance position. As mentioned inthe foregoing, the copper foil piece 31b' is arranged in a position thatcorresponds to the far point of the flash device in that instance.Further, in that instance, the switches 40b' and 41' are turned on.Accordingly, the output level of the AND gate 45' which is connected tothe copper foil piece 31b' becomes high. The embodiment is thus arrangedsuch that with the object located at a far distance, when the copperfoil pieces 31b' and 31c' are electrically connected to each other bythe brush 29, the RS-FF 49' is reset to bring the lens barrel 1 to astop. Further, in the same manner as has been described in theforegoing, when the object is located at a near distance and a highlevel pulse signal is produced from the focusing circuit 47' before thebrush 29 comes to electrically connect the copper foil pieces 31b' and31c', the lens barrel 1 is stopped from moving at that instant.

In this specific embodiment, the switches which are arranged to beturned on by the movement of the lens barrel 1 are disposed in thepositions corresponding to the far points of the flash device; and thepower supply to the magnet is arranged to be cut off to stop the lensbarrel 1 from further moving with these switches turned on in the eventof flash photography. This arrangement, however, may be replaced withsome other suitable arrangement. For example, a pin may be arranged toprotrude within the moving region of the lens barrel 1 at the time offlash photography to engage the lens barrel 1 in such a way as toprevent it from moving farther from the far point of the flash device;and this pin may be arranged to be shiftable in response to the focallength change-over of the optical system.

In accordance with the invention, as described in the foregoing, anautomatic focusing type camera capable of shifting the photo takingoptical system for one focal length to another is arranged to have theoptical system justly focused on a hyper-focal distance thereof when thedistance to an object to be photographed is undetectable; and, in theevent of flash photography, the maximum shifting extent toward theinfinity distance of the photo taking optical system is limitedaccording to the far point of the flash device which is determined bythe focal length of the photo taking optical system. The cameraaccording to the invention thus always ensures appropriate focusing inaccordance with changes which take place in the aperture F-number, thedepth of field as a result of the focal length change-over of the phototaking optical system. The invention thus gives a highly advantageouseffect on the camera.

While specific embodiments of the invention have been shown anddescribed in detail to illustrate the application of the inventiveprinciples, it will be understood that the invention may be embodiedotherwise without departing from such principles.

What I claim:
 1. A camera capable of shifting a photo taking opticalsystem thereof from one focal length to another, comprising:(a)automatic focusing means for automatically adjusting the focal point ofsaid photo taking optical system; (b) stopping means for stopping saidphoto taking optical system at a predetermined focusing positionirrespective of a distance to an object to be photographed when theobject distance is undetectable by said automatic focusing means; and(c) switching means for varying, in response to the focal lengthchange-over of said photo taking optical system, the position at whichsaid optical system is to be stopped by said stopping means.
 2. A cameraaccording to claim 1, wherein said photo taking optical system isarranged to begin to move in a predetermined direction in response to ashutter release operation.
 3. A camera according to claim 2, whereinsaid stopping means includes predetermined focusing position detectingmeans for detecting the state of said photo taking optical system whensaid optical system reaches said predetermined focusing position aftercommencement of movement of said optical system.
 4. A camera accordingto claim 3, wherein said switching means includes a switching member forvarying, in response to the focal length change-over of said phototaking optical system, the detecting position to be detected by saidpredetermined focusing position detecting means.
 5. A camera accordingto claim 4, wherein said stopping means includes priority determiningmeans arranged to render said stopping means inoperative when the objectdistance is detectable by said automatic focusing means.
 6. A camerahaving a flash device and being capable of shifting a photo takingoptical system thereof from one focal length to another, comprising:(a)automatic focusing means for automatically adjusting the focal point ofsaid photo taking optical system; (b) stopping means for stopping saidphoto taking optical system at a predetermined focusing positioncorresponding to a far point of said flash device in preference over thefocal point adjusting position of said automatic focusing means when theobject distance is farther than the far point of said flash device inthe event of flash photography; and (c) switching means for varying, inresponse to the focal length change-over of said photo taking opticalsystem, the position at which said optical system is to be stopped bysaid stopping means.
 7. A camera according to claim 6, wherein saidphoto taking optical system is arranged to begin to move in apredetermined direction in response to a shutter release operation.
 8. Acamera according to claim 7, wherein said stopping means includespredetermined focusing position detecting means for detecting the stateof said photo taking optical system when said optical system reachessaid predetermined focusing position after commencement of movement ofsaid optical system.
 9. A camera according to claim 8, wherein saidswitching means includes a switching member for varying, in response tothe focal length change-over of said photo taking optical system, thedetecting position to be detected by said predetermined focusingposition detecting means.
 10. A control device for a photographicoptical system changeable in focal length, comprising:(A) automaticfocusing means for automatically adjusting the focal point of saidphotographic optical system; (B) predetermined focal point setting meansfor setting said photographic optical system at a predetermined focalpoint when said automatic focusing means fails to detect the distance toan object; and (C) switching means for varying the predetermined focalpoint to be set by the predetermined focal point setting means inresponse to the focal length changeover of the photographic opticalsystem.
 11. A control device according to claim 10, wherein saidphotographic optical system is arranged to begin to move in apredetermined direction in response to a shutter release operation. 12.A control device according to claim 11, further comprising stoppingmeans for stopping said photographic optical system at a predeterminedfocusing position irrespective of the distance to an object to bephotographed when the object distance is undetectable by said automaticfocusing means, said stopping means including predetermined focusingposition detecting means for detecting the state of said photographicoptical system when said optical system reaches said predeterminedfocusing position at the commencement of movement of said opticalsystem.
 13. A control device according to claim 12, wherein saidswitching means includes a switching member for varying, in response tothe focal length changeover offset photographic optical system, thedetecting position to be detected by said predetermined focusingposition detecting means.
 14. A control device according to claim 13,wherein said stopping means includes priority determining means arrangedto render said stopping means inoperative when the object distance isdetected by said automatic focusing means.
 15. A control device for aphotographic optical system changeable in focal length with a flashdevice, comprising:(A) automatic focusing means for automaticallyadjusting the focal point of said photographic optical system; (B)predetermined focal point setting means for setting said photographicoptical system to a predetermined focal point when the distance to anobject to be photographed is farther than the furthest effectivedistance of the flash device; and (C) switching means for varying thepredetermined focal point to be set by the predetermined focal pointsetting means in response to the focal length changeover of thephotographic optical system.
 16. A control device according to claim 15,wherein said photographic optical system is arranged to begin to move ina predetermined direction in response to a shutter release operation.17. A control device according to claim 16, further comprising stoppingmeans for stopping said photographic optical system at a predeterminedfocusing position irrespective of the distance to an object to bephotographed when the object distance is undetectable by said automaticfocusing means, said stopping means including predetermined focusingposition detecting means for detecting the state of said photographicoptical system when said optical system reaches said predeterminedfocusing position at the commencement of movement of said opticalsystem.
 18. A control device according to claim 17, wherein saidswitching means includes a switching member for varying, in response tothe focal length changeover offset photographic optical system, thedetecting position to be detected by said predetermined focusingposition detecting means.
 19. A control device according to claim 18,further comprising stopping means for stopping said photographic opticalsystem at a predetermined focusing position irrespective of the distanceto an object to be photographed when the object distance is undetectableby said automatic focusing means, said stopping means includingpredetermined focusing position detecting means for detecting the stateof said photographic optical system when said optical system reachessaid predetermined focusing position at the commencement of movement ofsaid optical system.
 20. An operation control device for a photographicoptical system, comprising:(A) automatic focusing means forautomatically adjusting the focal point of said photographic opticalsystem; (B) predetermined focal point setting means for setting saidphotographic optical system at a predetermined focal point when saidautomatic focusing means fails to detect the distance to an object; and(C) switching means for varying the predetermined focal point to be setby the predetermined focal point, setting means in response to the focallength variation of the photographic optical system.
 21. A controldevice according to claim 20, wherein said photographic optical systemis arranged to begin to move in a predetermined direction in response toa shutter release operation.
 22. A control device according to claim 21,further comprising stopping means for stopping said photographic opticalsystem at a predetermined focusing position irrespective to the distanceto an object to be photographed when the object distance is undetectableby said automatic focusing means, said stopping means includingpredetermined focusing position detecting means for detecting the stateof said photographic optical system when said optical system reachessaid predetermined focusing position at the commencement of movement ofsaid optical system.
 23. A control device according to claim 22, whereinsaid switching means includes a switching member for varying, inresponse to the focal length changeover offset photographic opticalsystem, the detecting position to be detected by said predeterminedfocusing position detecting means.
 24. A control device according toclaim 23, wherein said stopping means includes priority determiningmeans arranged to render said stopping means inoperative when the objectdistance is detected by said automatic focusing means.
 25. An operationcontrol device for a photographic optical system, comprising:(A)hyperfocal condition setting means for setting said photographic opticalsystem in a hyperfocal condition; and (B) means for changing the setstate of said photographic optical system by said hyperfocal conditionsetting means in response to change in the focal length of saidphotographic optical system.
 26. A control device according to claim 25,wherein said photographic optical system is arranged to begin to move ina predetermined direction in response to a shutter release operation.27. A control device according to claim 26, further comprising stoppingmeans for stopping said photographic optical system at a predeterminedfocusing position irrespective of the distance to an object to bephotographed when the object distance is undetectable by said automaticfocusing means, said stopping means including predetermined focusingposition detecting means for detecting the state of said photographicoptical system when said optical system reaches said predeterminedfocusing position at the commencement of movement of said opticalsystem.
 28. A control device according to claim 27, wherein saidswitching means includes a switching member for varying, in response tothe focal length changeover offset photographic optical system, thedetecting position to be detected by said predetermined focusingposition detecting means.
 29. An operation control device for aphotographic optical system, comprising:(A) automatic focusing means forautomatically adjusting the focal point of said photographic opticalsystem; (B) predetermined focal point setting means for setting saidphotographic optical system to a predetermined focal point when thedistance to an object to be photographed is farther than the furthesteffective distance of the flash device; and (C) switching means forvarying the predetermined focal point to be set by the predeterminedfocal point setting means in response to change of the F-number at thefully open aperture resulting from change in the focal length of saidphotographic optical system.
 30. A control device according to claim 33,wherein said photographic optical system is arranged to begin to move ina predetermined direction in response to a shutter release operation.31. A control device according to claim 30, wherein said switching meansincludes a switching member for varying, in response to the focal lengthchangeover offset photographic optical system, the detecting position tobe detected by said predetermined focusing position detecting means. 32.A control device according to claim 31, further comprising stoppingmeans for stopping said photographic optical system at a predeterminedfocusing position irrespective of the distance to an object to bephotographed when the object distance is undetectable by said automaticfocusing means, said stopping means including predetermined focusingposition detecting means for detecting the state of said photographicoptical system when said optical system reaches said predeterminedfocusing position at the commencement of movement of said opticalsystem.
 33. An operation control device for photographic optical system,comprising:(A) setting means responsive to changing over to a flashexposure mode for setting said photographic optical system to aprescribed focal condition; and (B) switching means for changing saidprescribed focal condition to be set by said setting means in responseto change of the F-number at the fully open aperture resulting fromchange in the focal length of said photographic optical system.
 34. Acontrol device according to claim 33 wherein said photographic opticalsystem is arranged to begin to move in a predetermined direction inresponse to a shutter release operation.
 35. A control device accordingto claim 34, wherein said switching means includes a switching memberfor varying, in response to the focal length changeover offsetphotographic optical system, the detecting position to be detected bysaid predetermined focusing position detecting means.
 36. An operationcontrol device for a photographic optical system variable in focallength, comprising:(A) automatic focusing means for automaticallyadjusting the focal point of said photographic optical system; (B)predetermined focal point setting means for setting said photographicoptical system to a predetermined focal point when said automaticfocusing means fails to properly adjust the focal point of saidphotographic optical system; and (C) switching means for changing thepredetermined focal point so as to correspond to the focal length of thephotographic optical system in response to changes in focal length ofthe photographic optical system.
 37. An operation control device for aphotographic optical system variable in focal length, comprising:(A)automatic focusing means for automatically adjusting the focal point ofsaid photographic optical system; (B) predetermined focal point settingmeans for setting said photographic optical system to a predeterminedfocal point when said automatic focusing means fails to adjust the focalpoint of the photographic optical system in an appropriate flashingrange of said flash device, and (C) switching means for changing thepredetermined focal point so as to correspond to the focal length of thephotographic optical system in response to changes in focal length ofthe photographic optical system.